Telemetry system for slickline enabling real time logging

ABSTRACT

A system for communicating with a slickline tool is disclosed. The system includes a closed-loop electrical circuit including a surface module, a forward path, a tool, and a return path. The forward path includes a slickline cable.

BACKGROUND

Conventional slickline logging systems employ battery-poweredinstruments that record logging information for later retrieval once thetool returns to the surface. Logging parameters are programmed at thesurface, the tool is run into the bore hole where measurements are madeaccording to the programmed logging parameters, and the tool is returnedto the surface. The results of the logging session are evaluated and, ifthey are determined to be inadequate, the logging parameters are changedand another logging session is run.

Conventional wireline logging uses wireline cables that have a muchlarger diameter (on the to order of an inch or more) as compared withslickline cables (an eighth of an inch or less). This difference indiameter prevents wireline cables from being used in high-pressurewells.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a slickline system.

FIG. 2 illustrates a communication module.

FIG. 3 illustrates a modem connection between a surface module and aslickline tool via a slickline cable.

FIG. 4 illustrates a slickline cable with multiple coatings.

FIG. 5 illustrates a slickline cable with multiple coatings and aconductive shield.

FIG. 6 illustrates a slickline cable including a hard jacketed cable.

FIG. 7 illustrates a method for using a telemetry system for slicklineenabling real time logging.

DETAILED DESCRIPTION

In some embodiments of a telemetry system for slickline enabling realtime logging, such as that illustrated in FIG. 1, an insulated slicklinecable 105 and a well casing 110 provide an electrical connection betweena surface electronics module 115 and a tool 120, forming a completeelectrical circuit. In some embodiments, the tool 120 is a logging tool.The insulated slickline cable 105 provides a forward path for signalsfrom the tool 120 to the surface electronics module 115, or vice versa.The well casing 110, which in some embodiments is made of a conductivematerial such as steel, provides a return path for the signals. In someembodiments, the well casing 110 provides the forward path for thesignals and the slickline cable 105 provides the return path. In someembodiments, the well casing 110 does not extend the full length of thebore hole 140.

In some embodiments, the slickline cable 105 is stored on a draw worksor spool 125 and proceeds through a pulley or system of pulleys 130 andthrough a packing assembly 135. The packing assembly 135 provides a sealbetween the high pressures in the bore hole 140 and the ambient pressureat the surface. In some embodiments, the slickline cable 105 proceedsthrough a blow-out preventer 145 that enables personnel to seal the wellif, for example, the packing to assembly 135 fails. In some embodiments,the blow-out preventer 145 is a valve that is normally open when theslickline system is in operation but is automatically or manually closedin the event of a blow out. It will be understood that the system mayinclude other elements that are used in slickline logging systems.

In some embodiments, the slickline cable 105 is electrically andmechanically coupled to the tool 120. While in most slickline systemsthe coupling between the slickline cable 105 and the tool 120 is asturdy mechanical connection, capable of sustaining the connectionthrough the entire slickline operation, in most slickline systemsefforts are made to insure that there is no electrical connectionbetween the slickline cable 105 and the tool 120. In the embodimentillustrated in FIG. 1, however, it is intended that the slickline cable105 be electrically connected to the tool 120. The electrical andmechanical connection between the slickline cable 105 and the tool 120is a conventional connection between a cable and a relatively heavyload.

In some embodiments, the tool 120 includes sensors and actuators, suchas probes, pressure sensors, acoustic sensors, and other similar sensorsand actuators. In addition, the tool 120 may have stabilizers 150 thatare fixedly deployed or that deploy when the tool 120 is making certainmeasurements. In some embodiments, the tool's sensors, probes, and/orstabilizers have dual roles. In addition to their normal functions, theyprovide an electrical connection between the tool 120 and the wellcasing 110 when making contact with the well casing 110. In someembodiments, the tool has a special member (not shown) that is dedicatedto providing the electrical connection between the tool 120 and the wellcasing 110 and has no other function. In some embodiments, the tool hasa special member (not shown) that provides an electrical connection tothe well casing 110 and extends to maintain that electrical connectionwhen the tool 120 drops in the bore hole 140 below the lowest level ofwell casing 110. For example, such a member may be a cable on a reel inthe tool 120. The cable may have a magnetic conductor that attaches tothe well casing and the reel may extend and retract the cable as thetool 120 is lowered and raised. In some embodiments, the wall of thebore hole 140 below the well casing 110 is sufficiently conductive toform part of the return path and the connection from the tool 120 to thewall of the bore hole 140 is made through the means described above.

In some embodiments, the tool 120 is capable of operating in two modes:(a) a first mode in which the forward path and return path are presentallowing communication between the tool 120 and the surface equipmentmodule 115, and (b) a second mode in which such communications are notpossible or desired. For example, the tool 120 may operate in the firstmode in the bore hole to 140 above the lowest level of well casing 110and then transition to the second mode if it is lowered below the lowestlevel of well casing 110. In that example, the tool 120 could (a) beprogrammed with logging parameters when it is located such that it canoperate in the first mode, (b) be lowered until it must operate in thesecond mode, logging and storing data, and (c) be raised until it canoperate in the first mode at which time some or all of the logged data,or data based on some or all of the logged data, can be uploaded fromthe tool 120 to the surface equipment module 115 and new loggingparameters can be downloaded.

In some embodiments, the electrical connection between the tool 120 andthe well casing 110 is intended to be continuous or at least partiallycontinuous, such as, for example, when the electrical connection is madethrough a permanently deployed stabilizer. In some embodiments, theelectrical connection between the tool 120 and the well casing occursonly, for example, when a sensor is deployed to make a measurement andthe sensor makes contact with the well casing 110.

In some embodiments, the electrical connection between the tool 120 andthe well casing 110 is direct, such as, for example, when the electricalconnection is made by pressing a sensor against the well casing 110. Insome embodiments, the electrical connection is indirect. For example,the electrical connection may be capacitive. In such embodiments, avarying potential difference between the slickline cable 105 and thewell casing 110 may be used to represent data being transmitted to orfrom the tool 120. In some embodiments, the slickline cable 105 and/orthe well casing 110 may act as a transmission line.

In some embodiments, the surface electronics module 115 is directlyconnected to the slickline cable 105. For example, in some embodimentsthe slickline cable 105 has an electrical connection to a contact 155 onthe draw works or spool 125. The surface electronics module 115 has anelectrical connection to the contact 155 through, for example, a brush160 that presses against the contact 155 even while the draw works orspool 125 is rotating. The brush 160 and contact 155 allow the surfaceelectronics module 115 to connect to the slickline cable 105 providing aforward path to the tool 120. In some embodiments, the surfaceelectronics module 115 has an electrical connection 165 to the wellcasing 110, which provides a return path for the electrical connectionmade through the forward path through the slickline cable 105.

In some embodiments, a safety module 170 is provided. The purpose of thesafety module 170 is to control the amount of power flowing through theslickline cable 105 such that, should a short circuit occur between, forexample, the slickline cable 105 and the well casing 110, the powerflowing though the slickline cable will not be sufficient to ignite orexplode the gasses in the bore hole 140. The selection of the componentsin the safety module is conventional and is based on a number offactors, including the identity, pressure, and temperature of the gas inthe bore hole, standard ignition gas curves, the depth that the tool isexpected to penetrate in the well bore, and other similar parametersthat are known to practitioners of safety module art. In someembodiments, for example, the safety module 170 includes a zener barrierand a current limiting resistor. Alternative safety techniques may alsobe utilized in addition to, or as an alternative to, the above describedtechnique.

In some embodiments, the tool 120 and/or the surface electronics module115 include a communications module 200, such as that illustrated inFIG. 2. In some embodiments, the slickline cable 105 is connected to asingle-pole, double-throw switch 205. It will be understood that switch205 is not necessarily a mechanical switch such as that suggested byFIG. 2. It may be an electronic switch, employing electronics to makeand break the connections. Other switching techniques are possible.

In some embodiments, the switch 205 connects the slickline cable 105 tothe input of a differential amplifier 210 when it is in one position. Insome embodiments, the other input to differential amplifier 210 isconnected to the well casing 110. The differential amplifier rejects thenoise that is common to the forward path (the slickline cable 205) andthe return path (the well casing 110), and produces a modulated signalwith reduced common-mode noise at its output. In some embodiments thatsignal is provided to a demodulator 215, which demodulates the receivedsignal and produces a digital signal that is provided to the otherequipment in the tool 120 or surface electronics module 115, dependingon where the communications module is located.

In some embodiments, when the switch 205 is in the second position(i.e., the position shown in FIG. 2), it connects the slickline cable105 to the output of an amplifier 220, which amplifies the modulatedoutput of a modulator 225 and conditions the signal for transmissionover the slickline cable 105 with the return path (e.g., the well casing110) providing an electrical reference for the transmitted signal. Insome embodiments, the modulator receives input data that is to betransmitted from other equipment in the tool 120 or surface electronicsmodule 115, depending on where the communications module is located.

In some embodiments, as shown in FIG. 3, the tool 120 and the surfaceelectronics module 115 each contain a modem, 305 and 310 respectively.In some embodiments, the modems allow to half duplex or full duplexsignaling between the tool 120 and the surface electronics module 115using standard modem communication techniques.

In some embodiments, the resistance of the slickline cable 105 is toohigh for supplying electrical power to the tool 120 and the tool 120 ispowered by batteries. In some embodiments, the tool 120 is equipped witha battery charging device, such as a turbine driven by fluids flowing inthe bore hole. If, however, conditions are such that power can besupplied from the surface through the slickline cable 105, in someembodiments the power will be supplied as direct current or asalternating current and signals between the tool 120 and the surfaceelectronics module 115 will be modulated onto a carrier that operates ata suitable frequency such that the power and signals will not interferewith each other. In either case, the data rate depends strongly on theelectrical characteristics of the slickline cable 105, but in someembodiments will be initially set to be at least 600 bits per second. Insome embodiments, performance, e.g., bit error rate, will be monitoredat the tool 120 and at the surface electronics module 115 and the datarate will be adjusted as necessary. For example, if it is determinedthat the bit error rate of transmissions between the tool 120 and thesurface electronics module 115 are too high, the transmission rate maybe reduced. Alternatively, the transmission may be switched to adifferent modulation technique. Other transmission variables may bealtered to attempt to improve the bit error rate.

The data that is transferred between the tool 120 and the surfaceelectronics module 115 can be of almost any type. For example, in someembodiments, the tool 120 transmits logging data as it is collected. Thedata can be checked at the surface and new logging parameters can betransmitted from the surface electronic module 115 to the tool 120,without having to retrieve the tool 120 to the surface. In oneembodiment the surface electronics module 115 is coupled to a remotereal time operating center 175 so that data received from other remotewells may be used in making logging decisions for the well being logged.In one embodiment, the surface electronics module 115 transmits data tothe remote real time operating center 175. The transmitted data may bethe data received from the tool 120 or it may be data derived from datareceived from the tool 120. In one embodiment, the remote real timeoperating center 175 uses the transmitted data, and, optionally, datafrom other remote wells, to formulate new logging parameters for thetool 120. In one embodiment, the remote real time operating center 175transmits the new logging parameters to the surface electronics module115, which transmits the new logging parameters to the tool 120. The newlogging parameters transmitted to the tool 120 may be the same loggingparameters transmitted from the remote real time operating center 175 tothe surface electronics module 115 or they may be derived from thoselogging parameters.

Slickline cable is readily available from many manufacturers.Manufacturers can insulate the cable as specified. While a thin oxidecoating may be sufficient, a polymer or Teflon coating may performbetter under adverse conditions involving corrosive chemicals atelevated temperatures and pressures.

In some embodiments, as shown in FIG. 4, the slickline cable 105consists of a solid wire core 405, an inner coating or jacket 410 and anouter coating or jacket 415. In some embodiments, the outer coating 415is resistant to abrasions and smooth, to allow easy travel through thepacking assembly 135 and blow-out preventer 145. In some embodiments,the inner coating 410 is heat resistant. In some embodiments, one orboth of the coatings are good insulators.

In some embodiments, the outer coating 415 is an epoxy and the innercoating 410 is a polyolephine. In some embodiments, the outer coating415 is similar to the coating that is typically used on transformerwindings, with enhanced heat resistance and smoothness.

In some embodiments, the slickline cable 105 includes a conductiveshield 505 between the inner coating 410 and the other coating 415. Insome embodiments, the conductive shield 505 acts as the return path.

In some embodiments, the slickline cable 105 includes a hard jacketedcable, as illustrated in FIG. 6. In some embodiments, the hard jacketedcable includes three parts:

-   -   (1) an outer tube 605 made of steel; in some embodiments the        outer tube includes a stainless steel, similar to the stainless        steels used in a standard slickline cable; the type of steel,        i.e., the strength, corrosion resistance, etc., is selected        according to the environment that the cable is expected to        experience; the thickness of the outer tube 605 is selected (a)        to provide the strength necessary to pull and hold the tool 120        and the cable itself over the entire distance and depth the tool        120 is expected to operate in the bore hole 140 and/or (b) to be        flexible enough to maneuver through the bore hole 140, or at        least that portion of the bore hole to be surveyed by the        slickline tool;    -   (2) an insulating layer 610; in some embodiments the insulating        layer 610 is a high temperature insulator that has the property        of helping to maintain the form of the outer tube 605; in some        embodiments the insulating layer 610 comprises magnesium oxide;        and    -   (3) one or more conductors 615; in some embodiments the        conductor is copper wire; in some embodiments the conductor is a        solid wire; in some embodiments the conductor is a stranded        wire.        In some embodiments, the outer tube 605 acts as the return path        and one or more of the conductors 615 acts as the forward path.        In some embodiments, the one or more of the conductors 615 acts        as the forward path and one or more of the conductors 615 acts        as the return path. In some embodiments, the conductors 615 are        used to provide power to the tool 120.

A method for slickline logging, illustrated in FIG. 7, begins bypositioning the tool in a bore hole where it cannot communicate with thesurface electronics module via the telemetry system (block 705). Thetool then logs data (block 710). The tool is then positioned in the borehole such that it can communicate with the surface electronics modulevia the telemetry system (block 715). The tool then transmits data basedon some or all of the logged data to the surface electronics module(block 720). Then, if it a new logging session is desired or necessary,the surface electronics module transmits logging parameters to theslickline tool (block 730).

The proposed system makes possible the use of real time logging withslickline, something that has not been previously available. Wirelinelogging employs armored cables that are simply too large and too roughto function in slickline environments.

The text above describes one or more specific embodiments of a broaderinvention. The invention also is carried out in a variety of alternateembodiments and thus is not limited to those described here. Theforegoing description of the preferred embodiment of the invention hasbeen presented for the purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform disclosed. Many modifications and variations are possible in lightof the above teaching. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto.

The invention claimed is:
 1. A system for communicating with a tool,comprising: a closed-loop electrical circuit including: a surface modulelocated on a surface of the earth; a tool located in a well borehole; aforward path between the surface module and the tool, the forward pathcomprising an insulated slickline cable, the slickline cable beingmechanically coupled to the tool and to a device on the surface, theslickline cable being electrically coupled to the tool; and a returnpath between the surface module and the tool; and a safety modulecoupled to the forward path to prevent the power flowing in the forwardpath from reaching a level where it might cause a predetermined gas at apredetermined pressure and temperature to explode.
 2. The system ofclaim 1 wherein: the return path comprises a well casing.
 3. The systemof claim 1 wherein: the tool is any one of directly coupled to thereturn path and indirectly coupled to the return path.
 4. The system ofclaim 1 wherein: the return path comprises a well casing; the toolcomprises a member that makes electrical contact with the well casing.5. The system of claim 4 wherein the member is selected from one of: asensor, a stabilizer, a probe.
 6. The system of claim 1 wherein: thetool comprises a modem; and the surface module comprises a modem tocommunicate with the tool modem by way of the forward path and thereturn path.
 7. The system of claim 1 wherein: the insulated slicklinecable is coated with an outer coating and an inner coating, one of thecoatings being abrasion-resistant and the other coating beingheat-resistant.
 8. An insulated slickline cable, comprising: aconductive solid wire; a first insulating coating applied to the wire; asecond insulating coating applied to the wire on top of the firstinsulating coating; and a coupling attached to one end of the wire, thecoupling allowing a mechanical connection to a tool and an electricalconnection to the tool.
 9. The insulated slickline cable of claim 8wherein one of the coatings is heat-resistant and one of the coatings isabrasion-resistant.
 10. The insulated slickline cable of claim 8 whereinthe first coating comprises polyolephine and the second coatingcomprises an epoxy.
 11. The insulated slickline cable of claim 8 furthercomprising a conductive metal shield between the first insulatingcoating and the second insulating coating.
 12. A slickline toolcomprising: a forward path coupling allowing a mechanical and anelectrical connection to a slickline cable, the slickline cableproviding a forward path for a communication signal; a return pathcoupling allowing an electrical connection to a return path for thecommunication signal; and a communication interface comprising areceiver coupleable to the forward path to receive data and atransmitter coupleable to the forward path to transmit data; wherein thereturn path coupling is capable of making one of a direct electricalconnection to the return path and an indirect electrical connection tothe return path.
 13. The slickline tool of claim 12 wherein the returnpath coupling is capable of making a capacitive connection to the returnpath.
 14. The slickline tool of claim 12 wherein: the coupling to thereturn path comprises an electrically-conductive member that selectivelyextends from the tool.
 15. The slickline tool of claim 12 wherein thereturn path coupling is extendable.
 16. The slickline tool of claim 12comprising a mode of operation in which one or more of the forward pathand the return path are not always available.
 17. A method for slicklinelogging, comprising: positioning a slickline tool in a bore hole whereit cannot communicate with a surface electronics module via a telemetrysystem; logging data; positioning the slickline tool in the bore holewhere it can communicate with the surface electronics module via thetelemetry system; and transmitting data based on some or all of thelogged data from the slickline tool to the surface electronics module.18. The method of claim 17 further comprising: transmitting loggingparameters from the surface electronics module to the slickline tool.19. The method of claim 17 further comprising: transmitting data basedon the data received from the slickline tool from the surfaceelectronics module to a real time operations center; using thetransmitted data at the real time operations center along with data fromother wells to generate logging parameters; transmitting the loggingparameters from the real time operations center to the surfaceelectronics module; and transmitting commands based on the loggingparameters from the surface electronics module to the slickline tool.20. The method of claim 17 further comprising: using the flow of fluidsin the bore hole to charge a battery in the slickline tool.